How do I overcome the fear of cashiers?

Is it a fear of talking to them or cashiers in general? If talking to them then it could be social anxiety. You could go to a therapist and get anxiety medication and work yourself through it.

Work slowly on it. Help build up your own confidence until you realize there is nothing at all to fear.

Cashiers are just another person with a job. And most of the time they don't really care, they're just working to get money and to them you're just another customer.

By interacting with them more, and noticing what about Cashiers specifically bother you? Is it just the transaction with money?

You could make it easier at first, by bringing a friend along for example. Or, if you feel fearful in other social situations, work on them - it helps you overcome other more specific fears. Within time you may be able to go to a cashier by yourself, fighting the anxiety, till the fear starts to lessen.

Just remember that cashiers are people, just like you. When I worked at a cinema I had to do shifts on the concessions tills and the box office. I was always nervous of serving people, even when I served 1000+ people a day. Cashiers are just normal people, with normal problems and normal perspectives. Don't be afraid.

Just remember that they have to check out tons of customers everyday, and they probably are not judging you. If they do, they will likely forget about you as soon as they move on to the next customer. Other solutions include focusing on the products that you are buying and thinking about how badly you want them, and (although it may sound ridiculous) it's okay to be on your phone or be talking on the phone while the cashier is checking you out. This way, the cashier probably won't talk to you and will only focus on ringing up your items and getting paid.

I also had a fear of cashiers and suffered with major social anxiety. What helped me is the idea that, chashiers go through hundreds of people daily, they don't really notice our personal errors or shyness- some even understand. Its okay and the experience is usually short

Perhaps you could gradually work your way up to overcoming this fear. You could first go to a cashier with someone you know well and trust and gradually start to go on your own

Remember that they are simply people just like you and just like your family/friends. They won't laugh at you if you fumble with your wallet, or give the wrong amount of money. They are simply doing their job and the last thing on their mind is judging you.